Preparation of organic phosphates



Patented Sept. 13, 1949 UNITED STATES PATENT OFFICE PREPARATION OF ORGANIC PHOSPHATES Ingenuin Hechenbleikner, Norwalk, Conn., as-

signor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application December 26, 1947, Serial No. 794,117

6 Claims. (Cl. 260-461) I bromomethyl, fi-chloroethyl, cyclohexyl, benzyl,

phenyl, and i-chlorophenyl.

it has been discovered that a chlorothiophosphate of the above type may be readily prepared by reacting a bis(thiophosphon) sulfide of the general formula R1-0 s 8 0-21 l s i ni-o 0-3.

in which R1 and R2 have the meaning shown above, and n is a whole number, with a chlorinating agent selected from the group consisting of chlorine, sulfur monochloride, and sulfur dichloride.

A typical reaction in which bis(0,0-diethyl thiophosphono) disulfide is reacted with chlorine to produce 0,0-diethyl chlorothiophosphate may be illustrated as follows:

UyHcO E 5 002 5 i -s-s-i +2c1i UiHls OCElHE 2 P-Cl Bach huitable inert organic solvents may be employed in the process. Such solvents include carbon tetrachloride, chloroform, benzene, tolu- 2 ene, xylene, chlorobenzene, tetrachloroethane, methylene chloride, ethylene dichloride, and the The reaction is preferably carried out at a temperature within the range of from about 0 to 0. However, temperatures outside this range may be employed depending upon the type of reactants utilized. Cooling means may be necessary, since the reaction is somewhat exothermic, particularly in the early stages.

The invention is further illustrated by the following examples in which the parts are by weight.

Example 1 A mixture consisting of parts of bis(0,0-diethyl thiophosphono) trlsulflde dissolved in 375 parts of carbon tetrachloride was stirred and cooled in an ice bath. .4.4 parts of chlorine were distilled into the mixture during a period of about one hour, the temperature of the reaction mixture being maintained between 10 and 15 C. The cold solution was then mixed with a liter of ice water and stirred for one-half hour. The mixture was filtered and the filtrate allowed to stratify into two layers. The lower layer was removed and distilled under reduced pressure. 73 parts of 0,0-diethyl chlorothiophosphate, a colorless liquid boiling at 49-50 C./1 mm., were obtained in a yield of 78% based on the weight of the bis(0,0-diethyl thiophosphono) trisulfide used.

Example 2 The procedure of Example 1 was employed using 85 parts of bis(0,0-diethyl thiophosphono) disulfide, 3'75 parts of carbon tetrachloride, and '71 parts of chlorine. parts (72% yield) of 0,0-diethyl chlorothiophosphate were obtained.

Example 3 A mixture consisting of 108.5 parts of his (0,0- diethyl thiophosphono) tetrasulfide dissolved in 375 parts of carbon tetrachloride was stirred and cooled in an ice bath. 154 parts of sulfur dichloride were slowly added, while the temperature of the mixture was maintained between 10 and C. After standing at room temperature for one hour, the reaction mixture was distilled under reduced pressure to remove the carbon tetrachloride. Further distillation gave 100 parts of sulfur monochloride distilling at 45-50 (1/35 mm., followed by 80 parts (85% yield) of 0,0-diethyl chlorothiophosphate distilling at 65 C./ 5 mm.

Example 4 52.6 parts of sulfur monochloride were gradually added to a well-agitated solution of 85 parts of bis(0,0-diethyl thiophosphono) disulfide in 150 parts of carbon tetrachloride. At the end of one-half hour, the temperature of the mixture had risen to 50 C. and sulfur began to separate. After standing for 24 hours, the clear liquid was decanted from a semi-solid mass of sulfur and distilled under reduced pressure to remove the carbon tetrachloride. Furt er distillation gave '75 parts (86% yield)- of O, -diethyl-chlorothiophosphate.

In like manner other alkyl, aralkyl, and aryl chlorothiophosphate esters may be prepared by reacting the corresponding bis(thiophosphono) sulfide with a chlorinating agent selected from the group consisting of chlorine, sulfur monochloride, and sulfur dichloride.

While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not to be limited thereto, but is to be construed broadly and restricted solely by the scope of the appended claims.

I claim:

1. A method of preparing an organic chlorothiophosphate of the general formula in which R1 and R2 are chosen from the group consisting of alkyl, aralkyl, and aryl radicals, which includes the step of reacting a bis(thiophosphono) sulfide of the general formula in which R1 and R2 are chosen from the group consisting of allwl, aralkyl, and aryl radicals, and n is a whole number, with a chlorinating agent selected from the group consisting of chlorine, sulfur monochloride, and sulfur dichloride.

2. The method of claim 1 in which the reaction is carried out at a temperature within the range of from about to 60 C.

3. The method of claim 1 in which the reaction is carried out in the presence of an inert organic solvent.

4. A method of preparing a dialkyl chlorothlophosphate of the formula which includes the step of reacting a bis(dialkyl thiophosphono) sulfide of the formula elkyl-0 O-alkyl in which n is a whole number with chlorine.

5. A method of preparing a dialkyl chlorothiophosphate of the formula (S)u-P alkyl0 in which n is a whole chloride.

6. A method of preparing phosphate of the formula O-alkyl number with sulfur monoa dialkyl chlorothioride.

IN GENUIN' HECHENBLEIKNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,411 Romieux et al. June 15, 1937 2,060,815 MacAfee Nov. 17, 1936 2,403,792 Engelke July 9, 1946 

